Querying Uncertain Minimum in Wireless Sensor Networks
In this paper, the authors introduce two types of probabilistic aggregation queries, namely, Probabilistic Minimum Value Queries (PMVQ)s and Probabilistic Minimum Node Queries (PMNQ)s. A PMVQ determines possible minimum values among all imprecise sensed data, while a PMNQ identifies sensor nodes that possibly provide minimum values. However, centralized approaches incur a lot of energy from battery-powered sensor nodes and well studied in-network aggregation techniques that presume precise sensed data are not practical to inherently imprecise sensed data. Thus, to answer PMVQs and PMNQs energy-efficiently, they devised suites of in-network algorithms. For PMVQs, their in-network Minimum Value Screening algorithm (MVS) filters candidate minimum values; and their in-network Minimum Value Aggregation algorithm (MVA) conducts in-network probability calculation.